The present invention relates to a multifunction acoustic device used in a portable instrument such as a portable telephone.
There has been provided an acoustic device of the portable instrument in which a speaker is provided for generating sounds of calling signals, and a vibrating motor is provided for informing the receiver of calling signals without generating sounds. In such a device, since both of the speaker and the motor are mounted in the device, the device is increased in size and weight, and in manufacturing cost.
In recent years, there is provided a multifunction acoustic device in order to remove the above described disadvantages. The multifunction acoustic device comprises a speaker having a diaphragm and a permanent magnet magnetically connected to a voice coil mounted on the diaphragm of the speaker. The permanent magnet is independently vibrated at a low frequency of 100-150 Hz so as to inform the receiving of calling signals by the vibration of the case of the device, which is transmitted to the body of the user of the device.
FIG. 6 is a sectional view of a conventional electromagnetic induction converter disclosed in Japanese Utility Model Application Laid Open 5-85192. The converter comprises a diaphragm 506 mounted in a case 512 at a periphery thereof, a voice coil 509 secured to the underside of a central portion 507 of the diaphragm 506, a spring plate 511 mounted in the case 512, and a permanent magnet 510 secured to a central portion of the spring plate 511, inserted in the voice coil 509.
By applying a low or high frequency signal to the voice coil 509, the spring plate 511 is vibrated in the polarity direction Y of the magnet 510.
In the device, the diaphragm 506 and the spring plate 511 are relatively moved through the magnetic combination between the voice coil 509 and the magnet 510. Consequently, when a low frequency signal or a high frequency signal is applied to the voice coil 509, both of the diaphragm 506 and the spring plate 511 are sequentially vibrated. As a result, sounds such as voice, music and others generated from the device are distorted, thereby reducing the quality of the sound. In addition, vibrating both of the voice coil 509 and the magnet 510 causes the low frequency vibration of the magnet to superimpose on the magnetic combination of the voice coil 509 and the magnet 510, which further largely distorts the sounds.
FIG. 7 is a sectional view showing a conventional multifunction acoustic device. The device comprises a speaker diaphragm 603 made of plastic and having a corrugated periphery 603a and a central dome, a voice coil 604 secured to the underside of the diaphragm 603 at a central portion, and a magnet composition 610. The diaphragm 603 is secured to a frame 609 with adhesives.
The magnetic composition 610 comprises a lower yoke 605, a core 601 formed on the yoke 605 at a central portion thereof, an annular permanent magnet 602 mounted on the lower yoke 605, and an annular upper yoke 606 mounted on the permanent magnet 602. The lower yoke 605 and the upper yoke 606 are resiliently supported in the frame 609 by spring plates 607 and 608. A magnetic gap 611 is formed between a periphery 601a of the core 601 and an inside wall 606a of the upper yoke 606 to be magnetically connected to the voice coil 604.
When an alternating voltage is applied to the voice coil 604 through input terminals 612a and 612b, the speaker diaphragm 603 is vibrated in the direction Y to generate sounds at a frequency between 700 Hz and 5 KHz. If a low frequency signal or a high frequency signal is applied to the voice coil 604, the speaker diaphragm 603 and the magnetic composition 610 are sequentially vibrated, since the magnetic composition 610 and the speaker diaphragm 603 are relatively moved through the magnetic combination of the voice coil 604 and the magnet composition 610.
As a result, sounds such as voice, music and others generated from the device are distorted, thereby reducing the quality of the sound. In addition, the driving of both the voice coil 604 and the magnetic composition 610 causes the low frequency vibration to superimpose on the magnetic combination of the voice coil 604 and the magnetic composition 610, which further largely distorts the sounds.
FIG. 8 is a sectional view showing another conventional multifunction acoustic device. The device comprises the speaker diaphragm 603 made of plastic and having the corrugated periphery 603a and the central dome, the voice coil 604 secured to the underside of the diaphragm 603 at a central portion, and the magnet composition 610. The diaphragm 603 is secured to the frame 609 with adhesives.
The magnetic composition 610 comprises a lower yoke 703, core 601 formed on the yoke 703 at a central portion thereof, an annular permanent magnet 702 secured to the lower yoke 703, and annular upper yoke 606 having a peripheral wall 606b and mounted on the permanent magnet 702. The upper yoke 606 is resiliently supported in the frame 609 by spring plates 707 and 708. A first magnetic gap 701 is formed between, a periphery 601a of the core 601 and an inside wall 606a of the upper yoke 606 to be magnetically connected to the voice coil 604. A second gap 705 is formed between a periphery 703a of the lower yoke 703 and inside wall 606a of the upper yoke 606. A driving coil 706 is secured to the frame and inserted in the second gap 705.
When an alternating voltage is applied to the voice coil 604 through input terminals 612a and 612b, the speaker diaphragm 603 is vibrated in the direction Y to generate sounds at a frequency between 700 Hz and 5 KHz. If a low frequency signal or a high frequency signal is applied to the voice coil 604, the speaker diaphragm 603 and the magnetic composition 610 are sequentially vibrated, since the magnetic composition 610 and the speaker diaphragm 603 are relatively moved through the magnetic combination of the voice coil 604 and the magnet composition 610.
When a high frequency signal for music is applied to the voice coil 604, only the speaker diaphragm 603 is vibrated. Therefore, there does not occur distortion of the sound. Furthermore, when a low frequency signal is applied to the driving coil 706, only the magnetic composition 610 is vibrated, and the speaker diaphragm 603 is not vibrated.
However if a high frequency signal is applied to input terminals 612a, 612b, and a low frequency signal is also applied to input terminals 704a, 704b, the speaker diaphragm 603 and magnetic composition 610 are sequentially vibrated, thereby reducing the sound quality.
In the above described conventional devices, both the speaker diaphragm and the magnetic composition are vibrated when a low frequency signal or a high frequency signal is applied to the voice coil. This is caused by the reason that the low frequency vibrating composition is vibrated in the same direction as the high frequency vibrating direction.
An object of the present invention is to provide a multifunction acoustic device in which a vibrating member is not vibrated together with another vibrating member, thereby removing disadvantages of conventional devices.
According to the present invention, there is provided a multifunction acoustic device comprising a frame, a speaker diaphragm supported in the frame, a voice coil secured to the speaker diaphragm, a rotor having an annular rotor permanent magnet and rotatably supported in the frame, a stator having magnetic poles and provided in the frame, corresponding to the rotor, a stator coil for forming magnetic fluxes between the rotor permanent magnet of the rotor and the magnetic poles of the stator.
The device further comprises a cylindrical speaker yoke secured to a bottom of the frame at a central portion thereof, a speaker permanent magnet secured to a bottom of the speaker yoke, and a top plate secured to the top of the speaker permanent magnet, eccentric means provided on the rotor for vibrating the rotor during the rotation of the rotor.
The voice coil is disposed in a gap formed between the speaker yoke and the top plate.
The rotor permanent magnet is rotatably supported on the outside peripheral wall of the speaker yoke.
The eccentric means is a weight eccentrically provided on the rotor.
A driving circuit is provided for energizing the coil in the stator for rotating the rotor.